Topical immunotherapy with diphenylcyclopropenone (DPCP) is a treatment that can be used in patients with alopecia areata (AA) with more than 50% involvement of the scalp. The aim of this study is to assess the response of our patients with AA treated with topical immunotherapy with DPCP at the American University of Beirut-Medical Center (AUB-MC) and to characterize the favorable prognostic factors that predict response to treatment. This is a retrospective study of all patients diagnosed with AA at AUB-MC and treated with topical immunotherapy with DPCP over a period of 10 years. A total of 34 cases were included for analysis (19 males and 15 females). The majority of patients had limited AA (58.8%) with a mean of 39% of scalp involvement. The remaining patients had alopecia universalis (29.4%) and alopecia totalis (11.8%). The percentage of patients that responded to DPCP therapy in our series was 79.4% (n = 27). Ten patients achieved a maximal grade of 3 following treatment, six patients only achieved a grade of 1, and six patients achieved a grade of 2. Only five of the patients who responded to therapy achieved a grade of 4. Of the patients who responded, 10 relapsed (29.4%), and the mean time to relapse was 74.6 weeks from the initiation of treatment. No specific favorable prognostic factors were identified to predict response to treatment; however, a negative family history of atopy was found to be protective against relapse (P = 0.020). The most common side effect of therapy was itching (85.3%), followed by contact dermatitis (58.8%), blistering (17.6%), and cervical lymphadenopathy (17.6%). Limitations of this study were the retrospective nature of the study and the limited number of patients. This is, to the best of our knowledge, the first study on topical immunotherapy with DPCP in patients with extensive AA from a Middle Eastern population. This modality of treatment is effective in inducing a response in patients with extensive AA, although the response is partial in the majority of the cases. Benefits should be weighed against the high side-effect profile of therapy before initiation of treatment.