Background: The loss of follow up visits among HIV positive adults on antiretroviral therapy is a leading cause of morbidity and mortality in Tanzania. The loss of follow up visits brings a big challenge in Care and Treatment Centre (CTC) as many HIV clients are not attending clinics as scheduled Broad Objective: To assess the factors and challenges associated with the loss of follow up visits among HIV positive adults attending CTC in Ilala Municipal Council Methods: Cross sectional study design was conducted in Ilala Municipal Council involving HIV positive adults and health providers whereby data were extracted from CTC database and clients’ files. Data were obtained through structured questionnaires and were entered into Microsoft Excel and analyzed by using Stata version 13. Analysis for predictors was done using univariate and multivariate logistic regression where p value of <0.05 was considered as statistically significant. Results: 240 people were recruited in the study. 190 were patients, 50 were health workers, and most of the patients were females with the age ranging from 18-35 years amounting to 102 (54%). Lack of fare 72(60%), Stigma, shift from one clinic to another and use of traditional medicine found to be the factors contributing to the loss of follow up visits. However, lack of space (92%), shortage of health providers (94%), stigma and discrimination (90%), low motivation (94%) and work load (94%) were the challenges facing health providers during provision of services to HIV patients. Conclusion and Recommendations The study found that the recording system of the patients’ information were poor, there were some clients who died, others were shifted to other clinics but the CTC term them as the loss of follow up visits therefore the data recording system should be strengthened.