CCD photometry of the globular cluster M68

V and B photometry reaching V not less than 24 mag for the metal-poor globular cluster M68 has been obtained with the prime-focus CCD camera at the CTIO 4-m telescope. The main-sequence turnoff region of M68 is particularly well defined, allowing for detailed matching of the observed color-magnitude diagram with theoretical isochrones. Following a detailed examination, Y = 0.24, Fe/H = -2.0, E(B-V) = 0.07 mag, and (m - M)v = 15.25 mag are adopted. The best fit is obtained for isochrones with enhanced oxygen abundance, O/Fe = 0.7, and an age of 14 billion years. The sensitivity of this age estimate to changes in the principal parameters is discussed in the text. Isochrones and predicted colors from a grid of oxygen-enhanced models computed specifically for this analysis are presented. The luminosity function on the main sequence continuously rises to faint magnitudes, like those found for other metal-poor globular clusters (e.g., M13 and M15), observed with CCD cameras. (Author)