A low-cost platform is proposed for the growth and real-time monitoring of biological cells. The main components of the platform include a PMMA cell culture microchip and a multichannel lens-free CMOS (complementary metal-oxide-semiconductor) / LED imaging system. The PMMA microchip comprises a three-layer structure and is fabricated using a low-cost CO2 laser ablation technique. The CMOS / LED monitoring system is controlled using a self-written LabVIEW program. The platform has overall dimensions of just 130x104x115mm(3) and can therefore be placed within a commercial incubator. The feasibility of the proposed system is demonstrated using HepG2 cancer cell samples with concentrations of 5000, 10000, 20000, and 40000cells/mL. In addition, cell cytotoxicity tests are performed using 8, 16, and 32mM cyclophosphamide. For all of the experiments, the cell growth is observed over a period of 48h. The cell growth rate is found to vary in the range of 44 approximate to 52% under normal conditions and from 17.4 approximate to 34.5% under cyclophosphamide-treated conditions. In general, the results confirm the long-term cell growth and real-time monitoring ability of the proposed system. Moreover, the magnification provided by the lens-free CMOS / LED observation system is around 40x that provided by a traditional microscope. Consequently, the proposed system has significant potential for long-term cell proliferation and cytotoxicity evaluation investigations.