Abstract: A cast crankshaft with recesses or apertures provided in crank webs of the crankshaft and are formed in adjoining inner area of the casting material forming the main and crank pins by cores inserted therein prior to casting for the reduction of the weight and of the rotating out-of-round masses as well as of the counterweights thereof. A ratio of the smallest distance of the fillet of the crank pin from the outer surface line of the recess to the diameter of the crank pin lies between the values of 0.45 and 0.66, preferably at a ratio of about 1:2 with such distance being approximately as large as the distance between adjacent fillets at the crank and main pins from one another.