The development of new express methods for the analysis of the efficacy of anticancer therapy on the cellular level is highly desirable for the analysis of chemotherapeutic agent performance. In this paper we suggest the use of parameters of cell morphology determined by holographic microscopy and tomography for the effective label free quantitative analysis of cell viability under antitumor chemotherapy and thus of cytostatic agent efficacy. As shown, measured phase shifts and cell morphology change dramatically as a result of chemotherapy and depend strongly on the cell type and agent applied. Experimentally, a comparative analysis of the antitumor efficacy of the two cytostatics, cisplatin and dioxadet, that are commonly used for chemotherapy of disseminated ovarian carcinoma has been performed. The experiments were carried out on the Wistar rat model. An essential difference in the morphology of cells, both normal (erythrocytes) and cancerous, present in ascitic fluid taken from the non-treated group of rats and the groups treated with either dioxadet or cisplatin, has been observed. The results obtained can be interpreted as an indication of the antitumor performance of both cytostatics at the cellular level and as a demonstration of the higher efficacy of therapy with dioxadet as compared to that with cisplatin. Differences in cell morphology are suggested to be applied as quantitative markers of cell viability and cytostatic agent efficacy. The conclusions made are supported by a comparison with the results of recent experiments based on survival rates of laboratory animals treated with these agents.