Chlamydia and pelvic inflammatory disease (PID) are a very common sexually transmitted infection and disease, respectively. This article is about researching the correlation between chlamydia and pelvic inflammatory disease and how factors such as age, socioeconomic conditions, medical facilities, variants of the bacteria themselves can alter the outcomes of progression from chlamydia to PID found in the same population under study. Untreated chlamydia can cause more serious medical conditions such as pelvic inflammatory disease, infertility and ectopic pregnancy. Pelvic inflammatory disease is the most common sexually transmitted disease found especially in women. It is also a major cause of infertility in women. Chlamydia is also a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. Exposure to chlamydial infection can lead to a greater risk of pelvic inflammatory disease. Both STDs show different symptoms but are considered interconnected. Chlamydia infection, which in most cases shows very slow or no symptoms, if left untreated can lead to pelvic inflammatory disease and can further cause infertility. To determine the correlation between chlamydia and pelvic inflammatory disease, microRNAs were used as biomarkers in an experiment to diagnose bacterial growth infection. These microRNAs regulate chemokine cytokine responses which are the immune responses that occur during bacterial infections. In a study on two chlamydial variants of C. muridarum – CmVar001 and CmVar004 (Chlamydia muridarum is also a strain of bacteria that causes chlamydia) the microRNA expression shown by these bacterial variants was examined. The experiment was conducted in vitro and in vivo. In vitro, the growth of the variants was d...... half of the article ...... play an important role in the progression of the infection in women. These are some of the factors related to women, but there are also different variations of bacterial strains that can grow at different rates in women's bodies. Some variants grow faster than others. This growth rate influences the progression of the disease. The focus of this article is on the effects of C. trachomatis on the upper genitalia of women, but in one of the experiments it was also seen that more women who had previously been infected with gonorrhea were hospitalized for PID. Chlamydia is one of the causes of pelvic inflammatory disease if left untreated, but there are also other sexually transmitted infections that can lead to this disease. It also depends on the state of health, age, previous pregnancies and abortions, accessibility to health facilities which affect the progression or regression of infections.