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The aim of the investigation was to assess the influence of humins chalk, as a source of calcium in the feed, on the performance parameters, the quality parameters of eggs and the concentration of calcium and phosphorus in the blood serum of laying hens. The examination was made in the experimental room (precisely controlled conditions) where 36 laying hens (Lohmann Brown) were kept during 8 weeks in the battery system. During the experiment, the standard lighting program was applied; feed and water were available ad libitum. The birds were divided into 3 groups (12 hens in each of group) - control group (C) and two experimental groups (D-1 and D-2). Birds were feeding with the all-mash feed type J-297 prepared according to standard recipe, the content of calcium was 3,0%. The feed for the experimental groups contained the same amount of calcium as the feed for the control group but 0,25% (D-1) and 0,5% (D-2) of Ca was supplemented by addition of humins chalk. The performance parameters (laying rate, weight of laid eggs, the feed intake) as well as the quality parameters of eggs were controlled and analyzed. Eggs for examinations were collected in 4 series , i.e. on 14th (I series), 28th (II), 42nd (III) and 56th (IV) day of the experiment. The concentrations of total calcium and inorganic phosphorous in the blood serum collected after 2nd, 6th and 8th week of experiment were analyzed. The eggshells from both experimental groups were more resistant (breaking strength) than eggshells from group C, especially the samples collected during 2nd and 4th series of experiment (p=0,05). The eggs from groups D-1 and D-2 had higher weight but that fact was not statistically confirmed. The average concentrations of total calcium and inorganic phosphorus in the blood serum of hens from groups D-1 and D-2 were higher than in the blood serum of hens from control group, however, none of the obtained values exceed the physiological values. [ABSTRACT FROM AUTHOR]